An assembly having a roof part which is displaceable out of a frame is disclosed, for example, in European Patent Publication No. EP 0 059 859.
In this system, the roof part which can be displaced out of the frame has two outer edges spaced apart in the travel direction. One of these longitudinal edges is formed with two spaced apart hinge joints connecting it to the frame and disposed mirror symmetrically on opposite sides of a median plane perpendicular to the surface of the panel and, of course, to the centerline of this surface.
Along this centerline and at the opposite outer edge of the panel there is provided a locking or closure element by means of which the panel can be drawn sealingly against the frame structure This element can also be formed as a mechanism enabling the respective edge of the panel to be raised above the frame to open the roof. The closure element can be a toggle closure or the like.
The roof panel in the conventional roof assembly is generally outwardly convex. In order to ensure a uniform traction and watertight engagement of the panel on the ceiling strip or bead surrounding the roof opening, the panel closure element must apply extremely high closing forced when the panel is brought into its closed position. These forces must be sufficient to cause the panel in its closed position to flatten with elastic deformation and lie flat against the peripheral seal.